Conventionally, the coding method is the most popular approach to protect the secret of personal data. However, the coding method is found with some disadvantages, such as that the user fails to always remember the code, and that the user is at the risk of having his code to be broken by others. Therefore, bio-recognition methods by using personal bio-data, e.g., fingerprint, vocal password, handwriting, and iris have been gradually developed into sound and effective ways of data protection. The bio-recognition method has the advantage that since the biological feature is an integral part of a human body, one does not have to particularly memorize for the recognition, and such biological feature is naturally burglarproof. Furthermore, the protection method incorporating with fingerprint bio-feature is not only considered as security-tight, but also allows convenient application.
Personalized electronic products adapted with fingerprint recognition device generally available in the market usually have a sensor disposed at a pre-selected location to retrieve the fingerprint. However, for compromising production cost and the size of the device, the area with lateral ribs is comparatively smaller; therefore, the fingerprint data can only be retrieved by having the fingerprint to correctly press and cover up the sensor in sequence. If the location to press the fingerprint flushed against the sensor is not exact, it is impossible to retrieve correct and complete fingerprint data thus to fail the recognition. The retrieval of a correct and complete fingerprint by the smaller area sensor is further compromised by the sweat on the finger ball where can easily catch dust in the air or on any object to blur the fingerprint